Yellow, ultraviolet light stabilized, 1-olefin resin composition



United States Patent 3,361,707 YELLOW, ULTRAVIOLET LIGHT STABILIZED, l-OLEFIN RESIN COMPOSITION Gordon C. Newland, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Jan. 18, 1965, Ser. No. 426,355 7 Claims. (Cl. 260-41) ABSTRACT OF THE DISCLOSURE A stabilized normally solid thermoplastic composition consisting essentially of normally solid l-olefin resin and N-(p-phenylazophenyl) maleimide at a concentration of about 0.1 to about 10% by Weight of said resin.

This invention resides in the chemical arts. It pertains to l-olefin resins and relates to the problem of coloring them to the problem of stabilizing them relative to the degradative efliects of ultraviolet light.

In the manufacture of plastic articles it is often desirable to add an attractive color to the plastic composition. In the case of molded articles of thick sections the color is usually the result of a colorant milled into the plastic prior to molding. When the finished articles are fibers or fabric the color is often induced by dyeing. However, in the case of normally solid polymers of l-olefins, such as normally solid polyethylene and crystalline polypropylene, which are thermoplastic, synthetic resins which have gained a Wide-spread use as materials of construction, dyeing is diflicult to accomplish and a number of the dyes lack light fastness. Even in the case of articles molded from normally solid polymers of l-olefins, colors therein often fade on exposure to ultraviolet light. Hence, there is a need for colorants for normally solid polymers of l-olefins, which give attractive colors and which resist fading on exposure to ultraviolet light.

As is well known, normally solid polymers of l-olefins undergo photochemical degradation when exposed to causes rupture of the polymer chains and formation of' carbonyl (=C:O) groups. As this degradation progresses, articles manufactured from l-olefin polymers tend to crack, become brittle and lose tensile strength to the extent of mechanical failure. Hence, there is a problem inhibiting the ultraviolet light deterioration of l-olefin polymers. One solution to the problem is to add-to the plastic composition based on a l-olefin polymer a compound which inhibits its ultraviolet light degradation. However, many colorants either nullify or substantially reduce the ctfectiveness of such compounds as ultraviolet light stabilizers in l-olefin polymers.

This invention is based upon the discovery that N-(pphenylazophenyl)maleimide, when incorporated into 1- olefin polymers, is an attractive yellow colorant for them, has a high degree of light fastness, has high tinctorial properties, can be incorporated in l-olefin polymers by conventional compounding procedures and confers on l-olefin polymers a high degree of stability to embrittlernent by action of ultraviolet light.

In summary, this invention comprises a normally solid, yellow, thermoplastic composition consisting essentially of normally solid, l-olefin resin and N-(p-phenylazophenyl) maleimide at a concentration in a range from about 0.1 to about 10% by weight of said resin.

The normally solid, l-olefin resin in the normally solid yellow, thermoplastic composition of this invention consists essentially of at least one, normally solid, l-olefin polymer. Such a polymer, commonly referred to generically as a poly-a-olefin, is one which is derived from a l-monoolefinic hydrocarbon having 2-20 carbon atoms, generally 2-10 carbon atoms and usually 2-6 carbon atoms. It is also provided by the normally solid copolymers, which include graft polymers, addition polymers, block copolymers and the like, of l-monoolefinic hydrocarbons having 2-20 carbon atoms, generally 2-10 carbon atoms and usually 26 carbon atoms, as well as of these l-monoolefinic hydrocarbons and other compounds. Examples of a normally solid polymer derived from a 1- monoolefinic hydrocarbon having 220 carbon atoms include the linear and branched, low density and high density, crystalline and amorphous, normally solid homopolyrners and copolymers of ethylene, propylene, l-butene, isobutylene, l-pentene, 2-rnethyl-1-pentene, 3-methyl-lbutene, l-hexene, 3,3-dimethyl-l-butene, l-heptene, 1- octene, l-nonene, l-decene, 4-methyl-1-pentene, 4-methyll-hexene, S-ethylene-l-hexene, G-methyl-l-heptene, 6- ethyl-l-heptene, styrene, allyl benzene, and the like. Processes for preparing a normally solid l-olefin polymer are well known and described in detail in the prior art. See, for example, the U.S. patent, No. 2,153,553, to Fawcett et al., the U.S. patent, No. 2,912,429, to Cash and the U.S. patent, No. 2,917,500, to Hagemeyer et al. In general, a normally solid, l-olefin resin is a thermoplastic material which at 20 C. is solid. It includes the so-called poly-etolefin waxes which usually have average molecular weights in a range from about 3000 to about 12,000.

The normally solid, l-olefin resin of the l-olefin composition of this invention, in addition to at least one normally solid, l-olefin resin, can also comprise other polymeric components. Thus, it can comprise a normally solid resin derived from another l-monoolefinic hydrocarbon having 2-20 carbon atoms. It can comprise at a minor concentration a different kind of polymer, generally present as a physical property improver.

N-(p-phenylazophenyl)maleimide, also known as pphenylazomaleimanil, is a known compound. A reference which describes its synthesis is J. Chem. Soc. (1955), 2970. While under the concepts of this invention this additive is employed at a concentration in a range from about 0.1 to about 10% by weight of the resin, the preferred range when ultraviolet light stability is the primary objective is from about 0.5 to about 3% by weight, the preferred range when color is the primary objective is about 0.1 to about 5% by weight, and the preferred range when color and ultraviolet light stability stand about equal in objective, is about 0.5 to about 5% by weight of the 1- olefin resin.

The normally solid, l-olefin resin composition of this invention is made by incorporating the N-(p-phenylazophenyl)maleimide of this invention into the normally solid l-olefin resin. Generally, such incorporation is per- Components:

formed by any one of a number of known methods, such as, for example, roll compounding, extrusion, solvent mixing and the like. For instance, such incorporation can be performed by heating or otherwise softening the nor- This specific embodiment is made by admixing the components in an inert atmosphere in a C. W. Brabender Plastograph. The product thus obtained is a yellow, ultraviolet light stabilized, poly(1-butene) composition which mally solid resin to a workable consistency and then 5 can be formed as by injection molding into useful articles. working in, as by roll compounding, the additive of this Samples of these specific embodiments have been tested invention until a substantially uniform blend or dispersion for ultraviolet light stability. is obtained. Generally, such incorporation takes place In the first series of tests the samples were made from at the same time that other additives are normally ina normally solid polyethylene having a density of 0.918. cor-porated into the l-olefin resin and usually along With The formulation of each sample is indicated in the followsuch other .additives as the formulation of the particular ing table. The samples were made by the procedure depl'astic composition requires. scribed in connection with the formulation of Example The normally solid, yellow, thermoplastic composition 1. Each sample thu obtained was compression molded of this invention is useful in coatings and as a material into plates 0.125 and 0.060 inch thick. .of construction for shaped articles. Thus, the composition The 0.060 inch thick plates were placed outdoors at can be made into various shaped articles such as, for ex- Kingsport, Tenn. Periodically, infrared measurements ample, pellets, sheeting, films, bars, tubes, filaments, fibers, were made on the 0.060 inch plates to determine the inspecially shaped structural elements and the like as by crease in carbonyl content. The exposure time required conventional casting and molding techniques which into produce an increase of 10 units of carbonyl content clude extrusion, blow molding and the like. '20 was thereby determined for each sample.-

This invention is further illustrated by the following The 0.125 inch thick plate of each sample was cut into examples of various aspects thereof, including preferred ten specimens 0.5 inch x 1.5 inches and the specimens specific embodiments of the invention. This invention is were bent into U-shape and while thus stressed inserted not limited to these specific embodiments unless otherupside down in an aluminum channel 0.5 inch wide. wise indicated. While thus mounted under stress, the specimens of each Example 1 sample were'exposed to natural weathering outdoors at This example illustrates a specific embodiment of a Kmgspoft: T611117 Perwdlcally, th speclmens were inyellow polyethylene composition of this invention. spected for the development of stress cracks v1s1ble to the- The formulation Ofthis ambodimentis, unaided eye. When stress cracks had developed in half of the exposed specimens of a sample the exposure time Components: Parts by we g required to reach this condition was determined. This Normally Sohd polyethylelle 100 exposure time was considered to be the stress crack- '(P'P Y P YD 1 free life of the ample. Also observed for each sample This specific embodiment is made by hot roll comwas Color Change Of the Plate during this exposurepounding the components for 5 minutes with the front The results of this testing are Summarized in the roll being at 270 F. and the rear roll being at 220 F. lowing table.

Concen- Stress Days Exposure Re- Sample tration Crack quired for Increase Color Change N0. Additives in parts Free of 10 Units of During Exposure by wt. Life Carbonyl Content None 12 60 None. N-(p-phenylaz0phenyl)maleimide.. 1 51 360 D0. Lead chromate 5 12 Opaque to infrared.-. Slight darkening.

Sun Yellow (acommercialpigment)- 5 12 do Slight fading.

The specific composition thus obtained is a yellow, ultraviolet light stabilized material which can be shaped as by compression molding into useful articles.

Example 2 This example illustrates a specific embodiment of a yellow polypropylene composition of this invention.

The formulation of this composition is:

Components: Parts by Weight Normally solid polypropylene 100 N-(p-phenylazophenyl)maleimide 1 This specific embodiment is made by admixing the components in an inert atmosphere in a C. W. Brabender Pl-astograph. There is thus obtained a yellow, ultraviolet light stabilized, polypropylene composition which can be shaped as by injection molding and the like into useful articles.

Example 3 This example illustrates a specific embodiment of a yellow, poly(1-butene) composition of this invention.

The formulation of this specific embodiment is:

Parts by weight Normally solid poly(1-butene) .100 N-(p-phenylazophenyl)maleimide 1 Sample No. 2 corresponds to the specific embodiment of Example 1.

crystalline polypropylene having an inherent viscosity of 1.4. The samples were made according to the procedure set forth in connection with Example 2. The components of each sample consisted essentially of the crystalline polypropylene and the additives indicated in the'following table. The samples as made'were granulated and then injection molded into tensile bars ,5 inch thick and 2% inches long. Three tensile bar specimens of each sample were bent into a U and inserted upside down while thus bent into a channel inch wide. The tensile bar specimens thus mounted were then placed into a modified Atlas Twin-Arc Weather-Ometer [Anal. Chem. 25, 460 (1953)]. Periodically, the specimens were inspectedv for the development of stress cracks visible under 3 magnification. When all three specimens of a sample had developed 3X visible stress cracks, the stress crack free life of the sample was then determined, it being the averaged exposure in hours required to develop cracks in all three specimens. The specimens were also inspected for changes in color. The results of these tests are sumparting from the spirit and scope of the invention as described and claimed.

1 claim:

1. A normally solid, thermoplastic composition conmarized in the following table. 5 sisting essentially of normally solid l-olefin resin and Concen- Stress Sam pl tration Crack Color Change No. Additives in Parts Free During Exposure by Wt Life (Hrs) None 90 Slight yellowing. N-(p-phenylazophenyl)maleimide. l 1, 310 None. Lead ehromate 5. 140 Slight darkening. Titanium IV oxide 1. 90 Slight yellowing. Polyester Yellow 5GLS 1 330 None.

Sample No. 2 corresponds to the specific embodiment of Example 2.

The data show that the polypropylene composition of this invention has good color retention and outstanding weathering stability.

In another series of tests the samples where made from a normally solid poly(l-butene) having an inherent viscosity of 1.5. The samples were made according to the procedure of Example 3. The samples consisted essentially of the normally solid poly(l-butene) and the additives indicated in the following table. In each case the sample was granulated and injection molded into three tensile bars inch thick and 2%. inches long. The tensile bar specimens were bent into a U and while thus under stress inserted upside down in a /8 inch wide channel. While thus mounted the tensile bar specimens were placed into the modified Atlas Twin-Arc Weather-'Orneter. Periodically the specimens were inspected for the development of stress cracks visible under 3 magnification. The stress crack free life in hours, the averaged exposure time required to develop stress cracks in all three specimens, was thereby determined. The specimens were also inspected for color change. The test results are sum- N-(p-phenylazophenyl)maleimide at a concentration in a range from about 0.1 to about 10% by weight of said l-olefin resin.

2. A composition according to claim 1 wherein said concentration is in a range from about 0.5 to about 5% by weight of said l-olefin resin.

3. An ultraviolet light stabilized, yellow, thermoplastic composition consisting essentially of normally solid polyethylene and N-(p-phenylazophenyl)maleimide at a concentration in a range from about 0.5 to about 5% by weight of said polyethylene.

4. An ultraviolet light stabilized, yellow, thermoplastic composition consisting essentially of normally solid polypropylene and N-(p-phenylazophenyl)maleimide at a concentration in a range from about 0.5 to about 5% by weight of said polypropylene.

5. An ultraviolet light stabilized, yellow, thermoplastic composition consisting essentially of normally solid poly(l-butene) and N-(p-phenylazophenyl(maleimide at a concentration in a range from about 0.5 to about 5% by weight of said poly(l-butene).

6. Shaped articles of a normally solid, thermoplastic composition consisting essentially of normally solid l-ole- A marized in the following table. fin resin and N-(p-phenylazophenyl)maleimlde at a con- Concen- Stress 5211111118 tration Crack Color Change N o. Additives in Parts Free During Exposure by Wt. Life (Hrs) NOHP 135 Yellowed. N-(p-phenylazophenyl)maleimide. l 1, 950 None. Lead chromate 5 250 Darkened. Polyester Yellow 5GLS 1 390 None.

Sample No. 2 corresponds to the specific embodiment of Example 3.

These data show that N-(p-phenylazophenyl)maleimide in poly(1-butene) is light fast and confers on the l-olefin resin an exceptional stability to weathering.

Thus, this invention provides an ultraviolet light stabilized, attractive, light fast yellow, normally solid, l-olefin resin composition.

These and other features, advantages and specific embodiments will be readily apparent to those in the exercise of ordinary skill in the art after reading the foregoing disclosures. In this connection while specific embodiments of this invention have been described in considerable detail, variations and modifications can be eftected without de References Cited UNITED STATES PATENTS 3,105,059 9/1963 Van der Burg 26045.8

DONALD E. CZAJA, Primary Examiner. L. J. BERCOVITZ, Examiner.

I. WELSH, Assistant Examiner. 

